Committee weighs strict noise controls for data centers, including decibel caps and scheduled generator tests

Concerns about data-center noise — particularly low-frequency hums and generator testing — dominated technical discussion at the committee meeting. Will Calderon, an environmental engineer with Olsen, told the committee engineers rely on manufacturer specifications and worst-case assumptions when modeling noise from generators, chillers and cooling equipment. "We model that" using client-provided worst-case unit specifications, Calderon said.

Mitch Baer outlined proposed regulatory measures: maximum decibel limits at property lines (daytime standards in the 55–65 dB range, nighttime down to 45 dB with separate low-frequency thresholds), required worst-case 3‑D acoustic modeling (ISO 9613-2 or equivalent), third-party peer review paid by the applicant, and post‑construction compliance testing by a qualified independent acoustical engineer within 60 days of operational status and periodically thereafter. Baer also proposed that generators be enclosed in sound‑attenuating canopies or buildings achieving approximately a 25 dB reduction.

On generator testing, Baer recommended restricting routine testing to weekdays between 10 a.m. and 4 p.m., excluding holidays, and limiting monthly test duration to a maximum of about 60 minutes per generator (some jurisdictions cited lower thresholds of 30 minutes). Simultaneous multi-generator testing should be prohibited except when required for emergency preparation. Brad Hutchins (mechanical specialist) and Olsen staff said monthly partial-load tests are common and full-load tests are typically annual.

Residents urged stricter limits, noting that continuous low-level sounds are particularly disruptive. One commenter argued that even moderate decibel levels that are constant can interrupt sleep and quality of life. Baer acknowledged that continuous tonal sounds can be more irritating than intermittent louder events and said the county would regulate both steady-state and peak events.

Enforcement: Baer said compliance testing and peer review should be paid by the developer and that administrative fines and escalating penalties would be included in draft code to ensure compliance. The county will select peer-review parties and define testing scopes; the committee also asked staff to specify calibration standards and instruments used for compliance measurements.

Ending: The committee asked staff to refine numeric thresholds and testing protocols at the next meeting and to include air-pollution considerations for diesel generators in future drafts.